O-Prenylated aromatic aldehydes undergo smooth intramolecular dominoKnoevenagelhetero-Diels-Alderreactions with 4-hydroxycoumarins in the air- and moisture-stable ionic liquid [bmim[BF 4 under mild conditions to afforda novel class of cis-annulated pyranocoumarins in high yields. The recovered ionic liquid can be reused in successive runs with consistent activity.